1. Field of the Invention
This invention relates to a camera capable of magnetic recording and having a magnetic recording means for magnetically recording information into a magnetic recording part provided on a film.
2. Description of the Related Art
As one of known automatic exposure control methods for cameras, there is a so-called automatic exposure bracketing method in which exposures for a plurality of frames are made on a film with the exposure value being automatically shifted up and down from the correct exposure. According to this method, photographs of under-exposure or over-exposure can be intentionally obtained automatically in addition to a photograph of correct-exposure.
Further, as a means for use in the automatic exposure control of a camera, there is known an operation switch called "AE lock switch", which is arranged to hold a light value measured by the camera at a value obtained when the operation switch is operated by a camera operator. When the AE lock switch is operated, the camera performs automatic exposure control by deciding an exposure value on the basis of the luminance value of a photographed object obtained when the AE lock switch is operated, irrespective of the current luminance value of the photographed object.
However, in a case where a negative film is used for photographing and is sent to a photofinishing laboratory to have pictures printed, exposure control is performed at a film printing machine in such a way as to make the exposure value correct for each of frames of the film. Therefore, even if the exposure value is automatically shifted up and down from the correct exposure when taking a plurality of photographs in the automatic exposure bracketing mode, the actual printing service results in a plurality of photographs of one and the same exposure. Then, it becomes impossible to have pictures, or photographs, printed at the different rates of exposure as desired by the camera operator.
Similarly, even when photographs are taken with the AE lock switch operated, the exposure control performed at the film printing machine also causes the photographs to be of correct-exposure, which is not intended by the camera operator.
In a case where photographs, or shots, are taken with light-measuring and distance-measuring switches left in their on-states, like in a continuous shooting, it is preferable that the printing process is performed under one and the same condition. In such a case, the exposure control on the printing process also eventually causes the photographs to be of correct-exposure, which differs from an exposure intended by the camera operator.
Meanwhile, a camera disclosed in U.S. Pat. No. 5,027,140 is arranged to record, on a magnetic recording part provided on a film, information indicating that a printing process be performed under one and the same exposure condition so as to reproduce the exposure state taken at the time of photographing, i.e., information indicative of a so-called series scene. In this case, when printing is performed from the film, a plurality of frames at which that information has been recorded are printed under one and the same condition, so that photographs as intended by the camera operator can be obtained.
In the prior art example cited above, however, a signal or information indicative of a series scene is recorded only when a continuous shooting is performed. When the continuous shooting is not performed, the series scene indication signal is not recorded. Therefore, where any scene desired to be printed under the same condition is photographed, the camera operator has no choice but to perform the continuous shooting.
In the meantime, a camera disclosed in Japanese Patent Publication No. SHO 58-53327 is arranged to detect whether a light source used for photographing is a natural light (sunlight), a fluorescent light or a tungsten light and to record the result of detection on a film. In addition, there is also disclosed a method for obtaining adequate prints from a film exposed by such a camera and developed, by carrying out a color balance correcting process during printing. In cases where shots are taken under a fluorescent light illumination using a daylight-type film, prints obtained from the film tend to become greenish. In such a case, the color balance correcting process gives adequate prints by carrying out a printing process realizing that the pictures on the film have been taken under a fluorescent light condition. In addition, as a means for detecting the kind of a light source, there are also disclosed a method for detecting the color of illumination light and a method for detecting flickers included in the illumination light.
Further, a method of using an RGB sensor as a means for detecting the light source used for photographing is disclosed in Japanese Laid-Open Patent Application No. HEI 3-136026, and a method of detecting bright-lines included in a fluorescent light illumination is disclosed in Japanese Laid-Open Patent Application No. HEI 3-163538.
According to the prior art methods cited above, the kind of a light source used for illuminating an object to be photographed is detected before each photographing frame of the film is exposed to light. Therefore, in case where a plurality of frames are to be continuously photographed in succession by automatically shifting the exposure value from a correct exposure value, like in the case of automatic exposure bracketing (hereinafter referred to as "AEB"), a light source detecting action is unnecessarily carried out by the process of detecting the kind of a light source before each frame is exposed, even when it is preferable to keep conditions other than the exposure value constant. As a result, the speed of continuous shooting would be lowered, because an unnecessarily long period of time is required in taking pictures in the mode of continuous shooting. There is another problem that an error in detecting the kind of a light source would cause information indicative of different kinds of light sources to be recorded on a film, for example, even when pictures are taken under the same condition.
Similarly, in a case where photographing is continuously performed while performing an automatic exposure lock (hereinafter referred to as AE lock), photographs are taken with the exposure value intentionally fixed by the camera operator. Therefore, if the kind of a light source is detected before each exposure, a wrong kind of light source might be decided depending on the object or the composition of pictures, despite the AE lock being performed. Then, prints obtained by printing the photographs taken in this manner tend to deviate from what is expected from the AE lock.